To meet demands for diversification of video expression, recently, various video effects by operating and processing plural pictures by applying digital technology are realized, such as video effects of converting from one picture to other picture by dissolving or wiping, and putting a slave picture into a master picture and moving and rotating the slave picture therein, and further complicated processes are requested.
As the prior art relating to video processing, in the Japanese Laid-open Patent 4-115764/92, video or audio information stored in plural file devices is sent out to plural independent user terminals by passing through a file input changeover device. In this constitution, however, it is not guaranteed that plural pictures or sounds can be sent out to a same terminal.
In the Japanese Laid-open Patent 4-345985/92, comprising I/O for various information inputs and outputs, buffers for various pieces of information, a hard disk for storing information, and buses for connecting them, data is transferred synchronously by input and output of information between the hard disk and I/O for input and output through buffers corresponding to respective pieces of information. In this constitution, since it is not designed to operate and process plural input pieces of information and transfer as one piece of information, transfer of information over the transfer capacity of bus is not guaranteed.
As the means for combining pictures, the video editing apparatus disclosed in the Japanese Laid-open Patent 4-86163/92 and the video information processing apparatus disclosed in the Japanese Laid-open Patent 2-94781/90 are known.
In both of them, using a switch (changeover circuit), input pictures are stored in individual memory regions, and combined, but pictures of any arbitrary number of inputs cannot be combined, and transfer of sound and synchronism with picture are not disclosed.
Hitherto, if processing in the I/O for input and output differs with the kind of information, it was difficult to synchronize various data precisely. For example, when pictures and sounds are combined, in complicated video processing, once the pictures are stored in the memory and processed, which causes a time lag, and hence it results in a delay, through very slightly, from the sound.